1. Field of the Invention
The present general inventive concept relates to a processing system and method of processing pattern bitmap data for an image forming apparatus, such as a printer, and more particularly, to a processing system and method of processing pattern bitmap data for a printer adapted to divide the pattern bitmap data into data processing units, thereby enabling to improve a processing speed when the pattern bitmap data is read and written.
2. Description of the Related Art
Generally, when a user uses an application program of a terminal, such as a computer, to prepare characters, pictures and the like, and executes a print-out operation in a printer, a printer driver provides print data to be printed to the printer. The printer driver serves to convert the characters, pictures and the like prepared by the application program of the computer to the print data in a printer language interpretable by the printer.
The print data generated in the printer language by the printer driver is transmitted to the printer, and converted to bitmap data printable by the printer. The conversion process of the print data into the bitmap data is explained in detail hereinbelow.
First, an interpreter converts the print data to a printer inner language, and the print data converted to the printer inner language is divided into data processible by a decoder using a command parser. The divided data is decoded by the decoder.
The decoded data includes information relative to a source image, a pattern, a destination and a raster operation (ROP) and is converted into a bitmap graphic format. The “source image” denotes information relative to profiles, such as characters or pictures, included in the print data. The “pattern” denotes information relative to shades, slanting lines, and colors of characters or pictures. The “destination” denotes information relative to background, and the “ROP” denotes information relative to logical operation for each source image.
The decoded data is converted into bitmap data by a graphic processor, and stored in a memory per bit for printing by using an intrinsic illustration such as a symbolic command. The graphic processor converts source images, patterns and destinations to a bitmap format to generate a source image bitmap, a pattern bitmap and a destination bitmap, respectively, and generates final bitmap data using a logical operation designated by the ROP out of 256 logical operations.
Meanwhile, pattern data contained in the decoded data includes information relative to types of patterns and addresses, and the pattern data is stored in a memory of a printer. For that reason, the graphic processor extracts a relevant pattern bitmap from the memory during a logical operation. The pattern bitmap (also referred to as pattern bitmap data) generated by the graphic processor is temporarily stored in the memory, extracted again and printed.
However, when the pattern bitmap data is stored in the memory, the pattern bitmap data is stored at a position in proportion to where a pattern is printed out on a printing paper. For example, if pattern bitmap data is a 12 byte, and 5 bit length, and an address is a position which is a 30th bit with respect to a reference as a starting position, as illustrated in FIG. 1, storage must be arranged so that the pattern bitmap data begins from the bit 30 position. 2 bits are stored before 12 bytes, and then 3 bits are stored after 12 bytes.
At this time, because the pattern bitmap data has not started from a multiple byte position, and since the start position is the bit 30 position, the pattern bitmap data should be stored in a memory per bit for the entire length of 12 bytes and 5 bits.
In other words, for storing the pattern bitmap data having the 12-byte 5-bit length, a 101-bit writing operations (12 bytes×8 bits/byte+5 bits=96 bits+5 bits=101 bits) should be executed. Similarly, when extracting the pattern bitmap data from the memory, 101 bit-reading operations have to be performed.
According to a conventional method described above, when pattern bitmap data is stored in a memory from a graphic processor and then the pattern bitmap data is extracted from the memory, bit operations frequently occur where the pattern bitmap data is stored and extracted per bit, such that it takes a lot of time to store the pattern bitmap data in the memory and to extract the pattern bitmap data from the memory. In other words, there is a disadvantage in that it takes a relatively long time for a print-out to be executed.
In order to solve the afore-mentioned disadvantage, it becomes necessary to find a method for shortening a rendering time of the pattern bitmap data stored in the memory.